论文标题
水层向Mira变量BX CAM的天文动画
The Astrometric Animation of Water Masers towards the Mira Variable BX Cam
论文作者
论文摘要
我们报告了VLBI监测的观察结果（H $ _ {2} $ O）MASERS周围的Mira Vilable BX CAM，该观测是作为EAVN合成Stellar Maser Animations（Estema）项目的一部分进行的。从2018年5月至2021年6月获得37个时期的数据，时间间隔为3-4周，涵盖了大约三个出色的脉动期（$ p = \ sim $ 440 d）。特别是，在Vera站配备的双光束系统用于测量H $ _ {2} $ o MASER功能的运动学和视差。测量的视差$π= 1.79 \ pm 0.08 $ mas，与$ GAIA $ EDR3一致，并且以前测量的VLBI可视性在1- $σ$错误级别内。根据$ GAIA $ EDR3数据和环形43 GHz硅 - 莫诺氧化物（SIO）MASER分布的中心位置估计了中央恒星的位置。三维H $ _ {2} $ o Maser Kinematics表明，与Maser功能的空间和速度分布的速度为$ 13 \ pm4 $ km S $^{ - 1} $的速度为$ 13 \ pm4 $ km S $^{ - 1} $。此外，我们密集的监控程序实现的H $ _ {2} $ o maser动画表现出了BX CAM的折内波的传播。
We report VLBI monitoring observations of the 22 GHz water (H$_{2}$O) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Maser Animations (ESTEMA) project. Data of 37 epochs in total were obtained from 2018 May to 2021 June with a time interval of 3-4 weeks, spanning approximately three stellar pulsation periods ($P= \sim$440 d). In particular, the dual-beam system equipped on the VERA stations was used to measure the kinematics and parallaxes of the H$_{2}$O maser features. The measured parallax, $π=1.79\pm 0.08$ mas, is consistent with $Gaia$ EDR3 and previously measured VLBI parallaxes within a 1-$σ$ error level. The position of the central star was estimated, based on both the $Gaia$ EDR3 data and the center position of the ring-like 43 GHz silicon-monoxide (SiO) maser distribution imaged with the KVN. The three-dimensional H$_{2}$O maser kinematics indicates that the circumstellar envelope is expanding at a velocity of $13\pm4$ km s$^{-1}$, while there are asymmetries in both the spatial and velocity distributions of the maser features. Furthermore, the H$_{2}$O maser animation achieved by our dense monitoring program manifests the propagation of shock waves in the circumstellar envelope of BX Cam.
